Aos question

[DWBOX2000]

So the rough running when oil cap off means nothing?

Thanks for responding.

[stelan]

Originally Posted by DWBOX2000

So the rough running when oil cap off means nothing?

Thanks for responding.

No, that is normal, you are actually creating a vacuum leak by removing the cap
and engine will run rough.
It happens the same when:
running without oil cap (or non sealing one)
broken/cracked oil fill tube
broken dipstick tube
broken/cracked aos tubes
etc. etc.